diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1262cf45..ad86755b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * The blanket implementations for `FromPyObject` for `&T` and `&mut T` are no longer specializable. Implement `PyTryFrom` for your type to control the behavior of `FromPyObject::extract()` for your types.
 * The implementation for `IntoPy<U> for T` where `U: FromPy<T>` is no longer specializable. Control the behavior of this via the implementation of `FromPy`.
 * `#[new]` does not take `PyRawObject` and can reutrn `Self`  [#683](https://github.com/PyO3/pyo3/pull/683)
+* Use `parking_lot::Mutex` instead of `spin::Mutex` [#734](https://github.com/PyO3/pyo3/pull/734)
 
 ### Added
 
diff --git a/Cargo.toml b/Cargo.toml
index c41e6017..983ce2d8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,16 +19,16 @@ travis-ci = { repository = "PyO3/pyo3", branch = "master" }
 appveyor = { repository = "fafhrd91/pyo3" }
 
 [dependencies]
-libc = "0.2.62"
-spin = "0.5.1"
-num-traits = "0.2.8"
-pyo3cls = { path = "pyo3cls", version = "=0.8.5" }
-num-complex = { version = ">= 0.2", optional = true }
-num-bigint = { version = ">= 0.2", optional = true }
-inventory = "0.1.4"
 indoc = "0.3.4"
-unindent = "0.1.4"
+inventory = "0.1.4"
+libc = "0.2.62"
+num-bigint = { version = ">= 0.2", optional = true }
+num-complex = { version = ">= 0.2", optional = true }
+num-traits = "0.2.8"
+parking_lot = { version = "0.10", features = ["nightly"] }
 paste = "0.1.6"
+pyo3cls = { path = "pyo3cls", version = "=0.8.5" }
+unindent = "0.1.4"
 
 [dev-dependencies]
 assert_approx_eq = "1.1.0"
diff --git a/src/gil.rs b/src/gil.rs
index e56b7eb5..bebbde78 100644
--- a/src/gil.rs
+++ b/src/gil.rs
@@ -6,7 +6,6 @@ use crate::ffi;
 use crate::internal_tricks::Unsendable;
 use crate::types::PyAny;
 use crate::Python;
-use spin;
 use std::ptr::NonNull;
 use std::{any, sync};
 
@@ -124,7 +123,7 @@ struct ReleasePool {
     borrowed: ArrayList<NonNull<ffi::PyObject>>,
     pointers: *mut Vec<NonNull<ffi::PyObject>>,
     obj: Vec<Box<dyn any::Any>>,
-    p: spin::Mutex<*mut Vec<NonNull<ffi::PyObject>>>,
+    p: parking_lot::Mutex<*mut Vec<NonNull<ffi::PyObject>>>,
 }
 
 impl ReleasePool {
@@ -134,7 +133,7 @@ impl ReleasePool {
             borrowed: ArrayList::new(),
             pointers: Box::into_raw(Box::new(Vec::with_capacity(256))),
             obj: Vec::with_capacity(8),
-            p: spin::Mutex::new(Box::into_raw(Box::new(Vec::with_capacity(256)))),
+            p: parking_lot::Mutex::new(Box::into_raw(Box::new(Vec::with_capacity(256)))),
         }
     }